Question for you engine bay gurus regarding mystery switch

Catbert

Catbert

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Hi again everyone! I hope I haven't worn out my "welcome" yet as I'm only beginning to assess my newly acquired 1975 CSi. The wealth of information from all of the great members has already impressed!

This rotary switch lying above the passenger firewall and wired into a bundle along the AC lines has me stumped. Any ideas what this does and why it was installed?
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As you may have guessed, that isn't the way the car left the factory, so we would be speculating a bit on exactly what it is / what it does. I would assume that it is a hack that replaced the rotary switch on the console that controls the A/C. Perhaps someone didn't want to go to the trouble of disassembling the console assembly to replace the original switch, or perhaps an original switch wasn't available, so that one was patched in. Does the rotary switch in the console now do anything?

The device lying on the cam cover (visible on the upper right corner of your first picture) illustrates that the car's previous owner took a casual attitude toward originality.
 
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jmackro said:
As you may have guessed, that isn't the way the car left the factory, so we would be speculating a bit on exactly what it is / what it does. I would assume that it is a hack that replaced the rotary switch on the console that controls the A/C. Perhaps someone didn't want to go to the trouble of disassembling the console assembly to replace the original switch, or perhaps an original switch wasn't available, so that one was patched in. Does the rotary switch in the console now do anything?

The device lying on the cam cover (visible on the upper right corner of your first picture) illustrates that the car's previous owner took a casual attitude toward originality.
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Thanks for your comment. I haven't even begun to check everything out even though the car had a comprehensive inspection prior to purchase. I was informed the AC is not working due to leaking hoses, so I am ready for that. This coming weekend I intend to push every button, turn every dial, and throw every switch.

Your observation about the electrical device lying haphazardly on the valve cover is duly noted. I'm not anal about originality, but I am anal about things beging done right. :cool:
 
From the general configuration it appears to be a thermostat. Why there no clue unless they stuck the sensor capillary tube down the heater fan hole or are using it for a secondary purpose. Does look like an R134a adapter on the AC hose coupler.
 
The item on your valve cover appears to be your windshield washer pump that belongs on the bottom of the windshield washer tank.

The item sticking out from under your blower fan cover appears to be a thermalcouple. It certainly doesn’t belong there. It belongs in the face of your AC panel HVAC panel inside the car.
 
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In general, you will need to follow the wires and see where they lead you. As with the comment about originality, prior owner(s) seem to have been pretty casual about color coding on their wiring, making diagnostics even more fun.

You also seem to be missing a drain hose - https://www.wallothnesch.com/en/hea...-2-5-cs-3-0-csl-e9/catalog-picture-64-03.html - these not only direct water, they help keep exhaust gases from entering the drivers compartment.
 
sfdon said:
The item on your valve cover appears to be your windshield washer pump that belongs on the bottom of the windshield washer tank.

The item sticking out from under your blower fan cover appears to be a thermalcouple. It certainly doesn’t belong there. It belongs in the face of your AC panel HVAC panel inside the car.
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Doh! Yes. I removed it because my washer reservior is cracked and I need a new one. :rolleyes:
 
Keep in mind your model year AC wiring is different from earlier years.

No heater/AC changeover relay
Different blower switch
 
Catbert said:
Doh! Yes. I removed it because my washer reservior is cracked and I need a new one. :rolleyes:
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I forget why, but I removed my washer reservoir about 12 years ago and its still sitting on a shelf in the garage. I have yet to notice it missing.
 
Catbert said:
Thanks, Dlc! I took the advice from another member and purchased the book "The Hack Mechanic Guide to Vintage AC", so I have that to pour over once I begin my AC component upgrade project.
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there is plenty of threads on AC upgrades:

Blinkling

Thread 'DIY - Aftermarket Evaporator Installed In A Coupe'

Hi Team. I set out this year to find a replacement evaporator for the AC systems in our E9s and E3s (and E12s and E21s).

I found one (originally made for a 2007 Land Cruiser). It fits in the original box pretty well and it’s in my car working now. I’ll show you how I did it and then update you at some point in the near future as to whether there’s any advantage to it over the original parts. This is a work in progress and you are joining me in the experiment!

I want to emphasize that many members on this board have made their AC systems work pretty well using the original BMW...
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Stevehose

Thread 'Air conditioning upgrade photos/details'

For those contemplating such a project, I recently completed my York to rotary a/c compressor upgrade. Keeping with R-12. In prior posts on this subject there weren't a lot of specifics so I am trying to offer some here for the novices like me. Project included:

-switch from old York boat anchor to "Sanden style" 709 compressor and York mounting bracket from Johnjoysyl eBay seller ($190 for both and must be at least a 15lb weight savings):
IMG-20110716-00415.jpg



-replace old crusty condenser...
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Dan Wood

Thread 'DIY - Air Conditioning Updating with Sanden Compressor and Parallel Flow Condenser'

This DIY is subject to editing. More posts are being reviewed and information will be added.
I have tried to credit the people for their original posted information.
If there are errors or lacking information in here please let me know.

Air Conditioning Compressor and Bracket Selection

Posts were searched for this DIY:

Sanden compressor conversion brackets

Hello all, I have a very small one-man BMW restoration shop that I call L.C. Wylie & Co. and I also make and sell these brackets to convert your air conditioner to a modern Sanden type compressor. The original compressors are inefficient, expensive, and very hard to find a reliable new or...
e9coupe.com e9coupe.com

@Stevehose did a great write up in 2011 as follows and some info was used:

Air conditioning upgrade photos/details

For those contemplating such a project, I recently completed my York to rotary a/c compressor upgrade. Keeping with R-12. In prior posts on this subject there weren't a lot of specifics so I am trying to offer some here for the novices like me. Project included: -switch from old York boat...
e9coupe.com e9coupe.com

Book by...
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Ohmess said:
I forget why, but I removed my washer reservoir about 12 years ago and its still sitting on a shelf in the garage. I have yet to notice it missing.
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Maybe it needs a new home. ;)

I plan to drive my CSi often, so wipers with working washer nozzles is important.
 
Comments on a/c - you want the Sanden compressor, the largest condensor you can stuff into your car and a SPAL pusher fan in front of the condensor. (I have a SPAL pusher number 30102056).
 
Removing the AC faceplate is not that difficult. Removing the evaporator/blower or heater is an AWFUL job.

It is possible they wired in some kludge to adjust the blower speed. More likely they were either replacing or futzing with the AC switch. You can get to that by pulling the radio out, removing the AC face plate, and getting at the AC switches on the back side of that. If those white wires end up down in the AC, then you will either need to map out the circuit as currently built, or just cut all that crap out and rewire it according to the original plan. The latter would be my approach, since second guessing a long gone PO is a fools errand. Half the time the changes were made with a limited understanding of the system, and thus make no sense.
 
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